The emission of carbon dioxide (CO2) and other polluting gases from the burning of fossil fuels has received worldwide attention because of its implication in climate change, which threatens economies and environments. Accordingly, intensive research continues in the search for new materials that can efficiently, reversibly, and economically capture CO2 and other polluting gases. Ionic liquids (ILs) are particularly attractive for addressing this challenge because of their unique properties, such as low or negligible vapor pressures, wide liquid temperature ranges, generally high thermal stabilities, and tunable properties.
However, the ionic liquids thus far employed for this purpose (typically, amino-functionalized ILs) are beset with several drawbacks. A particular problem associated with many current IL capture materials is the high viscosity generated in these ILs on absorbing CO2. This substantial rise in viscosity adversely slows absorption kinetics, and hence, substantially increases operating costs. There are indications that the rise in viscosity in such ILs can be attributed to strong and dense hydrogen-bond networks during the reaction of CO2 with the IL (e.g., Gutowski, K. E., et al., J. Am. Chem. Soc., 2008, 130, 14690-14704). Moreover, current IL materials generally possess subpar CO2 absorption capacities and absorption rates for CO2 capture.